Magnetic tape cartridge

ABSTRACT

A magnetic tape cartridge has a cartridge casing, a single reel around which a magnetic tape is wound and which is contained in the cartridge casing for rotation and a leader pin fixed to the leading end portion of the magnetic tape. The leader pin is provided at its opposite ends with engagement portions which are brought into engagement with a tape drawing mechanism of a recording and reproducing system when the magnetic tape cartridge is loaded in the recording and reproducing system. The end face of each engagement portion is provided with a recess at which the tape drawing mechanism chucks the leader pin.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 10/406,211 filed Apr. 4,2003 U.S. Pat. No. 6,745,967, (which is a divisional of application Ser.No. 10/103,857 filed Mar. 25, 2002 U.S. Pat. No. 6,629,656, which is adivisional of application Ser. No. 09/852,635, filed May 11, 2001 U.S.Pat. No. 6,462,906, which is a divisional of application Ser. No.09/216,856, filed Dec. 21, 1998) U.S. Pat. No. 6,349,016, the disclosureof which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a magnetic tape cartridge, and moreparticularly to a magnetic tape cartridge comprising a cartridge casingand a single reel around which a magnetic tape is wound and which iscontained in the cartridge casing for rotation.

2. Description of the Related Art

There has been known a single reel magnetic tape cartridge comprising aflat cartridge casing which is formed by upper and lower shell halvesand is substantially square in shape and a single reel around which amagnetic tape is wound and which is contained in the cartridge casingfor rotation. Such a single reel magnetic tape cartridge has been usedfor retaining data of a computer or the like. A tape outlet opening isformed in a side wall of the cartridge casing and when the magnetic tapecartridge is used, i.e., when the magnetic tape cartridge is loaded in arecording and reproducing system as, for instance, an external storagefor a computer and information is to be recorded on the magnetic tape orinformation recorded on the magnetic tape is to be read, the magnetictape wound around the reel is drawn out through the tape outlet opening.

In such a magnetic tape cartridge of one type, a leader block is fixedto the leading end of a leader tape which is connected to the magnetictape and when the magnetic tape cartridge is not used, the magnetic tapeis fully wound, around the reel with the leader block fitted in the tapeoutlet opening to close the tape outlet opening. In the case of themagnetic tape cartridge of this type, when the magnetic tape cartridgeis loaded in the recording and reproducing system, a drive means in therecording and reproducing system engages with engagement teeth on thereel exposed outside at the central portion of the lower casing half anda tape drawing mechanism in the recording and reproducing system chucksthe leader block and draws the magnetic tape outside the cartridgecasing into a tape running path of the recording and reproducing system.

In another type, the tape outlet opening is closed and opened by a lidwhich is rotatable between a closing position where it closes the tapeoutlet opening and an opening position where it opens the tape outletopening, the lid being urged by a spring toward the closing position. Ahook member is fixed to the leading end of a leader tape which isconnected to the magnetic tape and when the magnetic tape cartridge isnot used, the magnetic tape is fully wound around the reel with the hookmember retracted inside the tape outlet opening and the lid held in theclosing position. In the case of the magnetic tape cartridge of thistype, when the magnetic tape cartridge is loaded in the recording andreproducing system, a drive means in the recording and reproducingsystem engages with engagement teeth on the reel exposed outside at thecentral portion of the lower casing half and a tape drawing mechanism inthe recording and reproducing system moves the lid to the openingposition, chucks the hook member and draws the magnetic tape outside thecartridge casing into a tape running path of the recording andreproducing system.

Recently, the recording and reproducing system (will be referred to as“tape drive system” hereinbelow) comes to require employment of a leaderpin about 3 mm thick in place of the leader block or the hook member.However attempts at meeting such requirement have encountered adifficulty that it is difficult for the tape drawing mechanism in thetape drive system to surely chuck such a thin leader pin.

SUMMARY OF THE INVENTION

In view of the foregoing observations and description, the primaryobject of the present invention is to provide a magnetic tape cartridgewhich is provided with a leader pin which can be surely chucked by thetape drawing mechanism in the tape drive system.

In the following description, a term “a magnetic tape” sometimes means“a magnetic tape with a leader tape connected thereto”.

The magnetic tape cartridge in accordance with the present inventioncomprises a cartridge casing, a single reel around which a magnetic tapeis wound and which is contained in the cartridge casing for rotation,and a leader pin fixed to the leading end portion of the magnetic tapeand is characterized in that the leader pin is provided at its oppositeends with engagement portions which are brought into engagement with atape drawing mechanism of a recording and reproducing system when themagnetic tape cartridge is loaded in the recording and reproducingsystem, and the end face of each engagement portion is provided with arecess at which the tape drawing mechanism chucks the leader pin.

With this arrangement, though simple in structure, the tape drawingmechanism of the recording and reproducing system can surely chuck theleader pin.

It is preferred that each engagement portion be provided with a smallerdiameter portion and a flange on the outer side of the smaller diameterportion and the recess be formed on the outer end face of the flange atthe center thereof.

For example, the leader pin may comprise a body portion provided withthe aforesaid engagement portions at its opposite ends and a clampmember which is press-fitted on the body portion sideways with theleading end portion of the magnetic tape sandwiched therebetween.

With this arrangement, the leader pin can be easily fixed to the leadingend portion of the magnetic tape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a magnetic tape cartridge inaccordance with an embodiment of the present invention with the slidedoor closed,

FIG. 2 is a perspective view showing the magnetic tape cartridge withthe slide door opened,

FIG. 3 is a side view partly cutaway showing a basic appearance of theleader pin,

FIG. 4A is an exploded perspective view of a first specific example ofthe leader pin,

FIG. 4B is a cross-sectional view of the leader pin,

FIG. 5 is an exploded perspective view of a second specific example ofthe leader pin,

FIG. 6A is a cross-sectional view of the second specific example of theleader pin in an assembled stated,

FIG. 6B is a view similar to FIG. 6A but showing a modification of thesecond example,

FIG. 6C is fragmentary cross-sectional illustrating another modificationof the second

FIG. 7 is an exploded perspective view another modification of thesecond example,

FIG. 8 is an exploded perspective view specific example of the leaderpin,

FIG. 9 is an exploded perspective view of a fourth specific example ofthe leader pin,

FIG. 10 is an exploded perspective view of a fifth specific example ofthe leader pin,

FIG. 11A is an exploded cross-sectional view of the fifth example,

FIG. 11B is a cross-sectional view of the fifth example in an assembledstate,

FIGS. 12A and 12B are schematic cross-sectional views for illustrating asixth specific example of the leader pin,

FIGS. 13A and 13B are schematic cross-sectional views for illustrating amodification of the sixth specific example,

FIGS. 14A and 14B are schematic cross-sectional views for illustratinganother modification of the, sixth specific example,

FIG. 15 is a schematic side view of a seventh specific example of theleader pin,

FIGS. 16A and 16B are cross-sectional views taken along line XVI—XVI inFIG. 15 before and after clamping the magnetic tape,

FIGS. 17A and 17B are views similar to FIGS. 16A and 16B but showing amodification of the seventh example,

FIG. 18A is a fragmentary perspective view of an eighth specific exampleof the leader pin,

FIG. 18B is a cross-sectional view of the eighth example,

FIG. 18C is a view similar to FIG. 18B but showing a modification of theeighth example,

FIG. 18D is a cross-sectional view showing the leading end portion ofthe magnetic tape wound around the leader pin,

FIG. 19A is fragmentary perspective view of another modification of theeighth example,

FIG. 19B is a cross-sectional view of the modification,

FIG. 19C is a view similar to FIG. 19B but showing a still anothermodification of the eighth example,

FIG. 20 is a side view of a ninth example of the leader pin,

FIGS. 21A to 21C are cross-sectional views taken along line XXI—XXI inFIG. 20 showing variations of manner of connecting the leader tape tothe leader pin,

FIG. 21D is a vertical cross-sectional view of FIG. 20 showing anothervariation of manner of connecting the leader tape to the leader pin,

FIG. 22 is a side view showing a modification of the ninth example,

FIG. 23 is an exploded side view of a tenth specific example of theleader pin,

FIG. 24A is a cross-sectional view taken along line A—A in FIG. 23,

FIG. 24B is a cross-sectional view taken along line B—B in FIG. 23,

FIG. 25A is a vertical cross-sectional view of a eleventh example of theleader pin,

FIGS. 25B and 25C are views similar to FIG. 25A but showingmodifications of the eleventh example,

FIG. 26 is a cross-sectional view taken along line XXVI—XXVI in FIG.25A,

FIG. 27 is a view for illustrating the dimensions of important parts ofthe eleventh example,

FIG. 28 is a vertical cross-sectional view of a twelfth example of theleader pin,

FIG. 29 is a perspective view of a thirteenth example of the leader pin,

FIG. 30 is a perspective view of the pin half in the thirteenth example,

FIG. 31 is an exploded side view of the leader pin of the thirteenthexample,

FIG. 32 shows cross-sections of the thirteenth example taken alongdifferent planes,

FIG. 33 is a cross-sectional view for illustrating a modification of thethirteenth example,

FIG. 34 is an exploded side view of a fourteenth specific example of theleader pin,

FIGS. 35A and 35B are cross-sectional views taken along lines A—A andB—B in FIG. 34,

FIGS. 36A to 36C are cross-sectional views for illustrating tapeclamping operation of the fourteenth example,

FIG. 37 is an exploded perspective view of a fifteenth specific exampleof the leader pin,

FIG. 38 is a perspective view of the fifteenth example in an assembledstate,

FIG. 39 is a cross-sectional view of the fifteenth example,

FIG. 40 is an exploded perspective view of a sixteenth specific exampleof the leader pin,

FIGS. 41A and 41B are views showing different manners of connecting theleader tape to the magnetic tape,

FIGS. 42A to 42C are views showing different manners of clamping theleading end portion magnetic tape by the leader pin of the precedingexamples,

FIG. 43 is a perspective view of a modification of the clamp member,

FIG. 44 is view for illustrating an example of the manner forpress-fitting the clamp member shown in FIG. 43 on the pin body,

FIG. 45 is a view for illustrating a method of bonding the magnetic tapeto the leader pin by use of hot-melt adhesive tape,

FIG. 46 is a perspective view of a leader pin of another example,

FIG. 47A is a fragmentary perspective view of a leader pin of stillanother example,

FIGS. 47B and 47C are fragmentary perspective views showingmodifications of the leader pin,

FIGS. 48 and 49 are perspective views showing the manner of forming aleader pin-magnetic tape assembly,

FIG. 50 is a transverse cross-sectional view of FIG. 49, view showing

FIG. 51 is a fragmentary cross-sectional view showing the inside of themagnetic tape cartridge near the tape outlet opening 2,

FIG. 52 is a cross-sectional view taken along line X—X in FIG. 41,

FIG. 52 is a fragmentary perspective a modification of the guidesurface,

FIG. 53 is a fragmentary perspective view showing another modificationof the guide surface,

FIG. 54 is a fragmentary perspective view showing still anothermodification of the guide surface,

FIG. 55A is a fragmentary cross-sectional view showing still anothermodification of the guide surface, and

FIG. 55B is a fragmentary cross-sectional view showing still anothermodification of the guide surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 and 2, a magnetic tape cartridge in accordance with anembodiment of the present invention comprises a cartridge casing 1formed by upper and lower casing halves 1 a and 1 b and a single reel(not shown) around which a magnetic tape is wound and which is supportedfor rotation in the cartridge casing 1. A tape outlet opening 2 throughwhich the magnetic tape is drawn out is formed in one end face of thecartridge casing 1 near a corner thereof. A slide door 3 for opening andclosing the tape outlet opening 2 is mounted in the cartridge casing 1to be slidable back and forth between a closing position where it closesthe tape outlet opening 2 and opening position where it opens the same.The slide door 3 is urged toward the closing position by a spring notshown disposed between a side face of the cartridge casing 1 and theslide door 3.

As shown in FIG. 2, a leader pin 4 fixed to the leading end of themagnetic tape is held inside the tape outlet opening 2. When themagnetic tape cartridge is loaded in a tape drive system, a reel drivemeans of the tape drive system is brought into engagement withengagement teeth (not shown) on the reel which is exposed in the bottomface of the cartridge casing 1 at the center thereof and a tape drawingmechanism of the tape drive system pushes the front end face 3 a of theslide door 3 to open the slide door 3. Further the tape drawingmechanism chucks the leader pin 4 and pulls the leader pin 4 into thesystem, whereby the magnetic tape is set in the tape drive system sothat data can be recorded on or read out from the magnetic tape.

A knob 5 for inhibiting erasure and write projects outside in one sideface of the cartridge casing 1.

As shown in FIG. 3, the leader pin 4 basically comprises a main portion11 at which the leading end portion of the magnetic tape is clamped, apair of small diameter portions 12 which extend from the upper and lowerend of the main portion 11 and a pair of flanges 13 which are formed onthe outside of the small diameter portions 12. The small diameterportions 12 form an engagement portions which are brought intoengagement with the tape drawing mechanism of the tape drive system.Each of the flanges 13 is provided at the center of its end face with aconical recess 13 a at which the tape drawing mechanism chucks theleader pin 4. The main portion 11 is substantially equal in length tothe width (½ inches) of the magnetic tape.

Examples of the specific structure of the leader pin 4 will bedescribed, hereinbelow. FIG. 4A is an exploded perspective view of theleader pin 4 of a first example and FIG. 4B is a cross-sectional view ofthe same. As shown in FIGS. 4A and 4B, the leader pin 4 of the firstexample comprises a body portion 15 of metal or hard plastic and a clampmember 16 of metal or hard plastic. The body portion 15 has a relativelythick middle portion, a pair of inner flanges 14 on opposite ends of themiddle portion, a pair of small diameter portions 12 on the upper andlower sides of the inner flanges 14 and a pair of outer flanges 13 onthe upper and lower sides of the small diameter portions 12. The clampmember 16 has an axial hole which extends over the entire length of theclamp member 16 and opens outward through a slit 16 a extending over theentire length of the clamp member 16. The clamp member 16 ispress-fitted on the middle portion of the body portion 15 between theinner flanges 14 through the slit 16 a with the leading end portion ofthe magnetic tape 10 pinched between the inner wall surface of the axialhole of the clamp member 16 and the outer surface of the middle portionof the body portion 15 a, whereby the leading end portion of themagnetic tape 10 is fixed to the leader pin 4.

With this arrangement, the leading end portion of the magnetic tape 10can be easily and surely fixed to the leader pin 4, and the conicalrecesses on the outer flanges 13 makes it feasible for the tape drawingmechanism of the tape drive system to surely chuck the leader pin 4.

The clamp member 16 may be formed of shape memory alloy instead ofelastic material. In this case, the clamp member 16 is heated and fittedon the middle portion of the body portion 15 between the inner flanges14 through the slit 16 a with the leading end portion of the magnetictape 10 pinched between the inner wall surface of the axial hole of theclamp member-16 and the outer surface of the middle portion of the bodyportion 15. Thereafter the clamp member 16 is cooled to normaltemperatures, whereby the axial hole of the clamp member 16 is reducedin its inner diameter under shape memory effect and the leading endportion of the magnetic tape 10 is clamped on the outer surface of thebody portion 15.

Examples of the specific structures of the leader pin which are providedwith a tape positioning means for positioning the leading end portion ofthe magnetic tape 10 with respect to the leader pin will be described,hereinbelow.

FIG. 5 shows a leader pin of a second example. As shown in FIG. 5, theleader pin of this example comprises a pin body 114 of metal or hardplastic. The pin body 114 has a pair of flanges 13 on opposite endsthereof and a shaft portion 115 which extends between the flanges 113and is substantially uniform in diameter. A resilient clamp member 116which is larger than the shaft portion 115 in outer diameter and issmaller than the shaft portion 115 in length is press-fitted on themiddle portion of the shaft portion 115. When the clamp member 116 ispress-fitted on the middle portion of the shaft portion 115, the smalldiameter portions 12 (FIG. 3) are formed on opposite sides of the clampmember 116. A groove 115 a is formed on the shaft portion 115 to extendin the longitudinal direction of the pin body 114.

The clamp member 116 has an axial hole which extends over the entirelength of the clamp member 116 and opens outward through a slit 116 aextending over the entire length of the clamp member 116. A flange 117is formed on one edge of the slit 116 a of the clamp member 116 toproject toward the longitudinal axis of the clamp member 116.

The clamp member 116 is press-fitted on the shaft portion 115 of the pinbody 114 with the flange 117 engaged with the groove 115 a as shown inFIG. 6A. By bringing the leading edge of the magnetic tape 10 intoabutment against the inner surface 117 a of the flange 117 when clampingthe leading end portion of the magnetic tape 10 between the pin body 114and the clamp member 116, the magnetic tape 10 can be easily positionedwith respect to the leader pin 4. It is preferred that the clamp member116 be formed of deposition hardened steel such as SUS631 in order toincrease resiliency of the clamp member 116.

In the case of this example, since the shaft portion 115 of the pin body114 is circular in cross-section, the main portion 11 (FIG. 3) formed byfitting the clamp member 116 on the shaft portion 115 cannot be circularin cross-section. When the shaft portion 115 is in such a shape thatforms circular cross-section together with the clamp member 116 as shownin FIG. 6B, the main portion 11 formed by fitting the clamp member 116on the shaft portion 115 can be circular in cross-section.

Further by forming a groove 117 b on the base of the inner surface 117 aof the flange 117 and inserting the leading end of the magnetic tape 10in the groove 117 b as shown in FIG. 6C, positioning of the leading endportion of the magnetic tape 10 with respect to the leader pin can bemore facilitated.

Further when a short groove 115 b is formed on the shaft portion 115 inperpendicular to the groove 115 a to be connected to the groove 115 a atone end thereof and a projection 116 b is formed on the clamp member 116at one end as shown in FIG. 7 so that the projection 116 b is receivedin the short groove 115 b when the clamp member 116 is fitted on the pinbody 114, positioning of the magnetic tape 10 with respect to the leaderpin in the axial direction thereof can be facilitated by bringing a sideedge of the magnetic tape 10 into abutment against the projection 116 b.

FIG. 8 shows a leader pin of a third embodiment in which positioning ofthe magnetic tape 10 with respect to the leader pin in the axialdirection thereof is facilitated. The leader pin of this example differsfrom that of the second example in that the shaft portion 115 is notprovided with the groove 115 a and accordingly the clamp member 116 isnot provided with the flange 117, and instead the clamp member 116 isprovided with a pair of arcuate shoulders 116 c extending from the slit116 a on opposite ends of the clamp member 116. The magnetic tape 10 ispositioned with respect to the leader pin in the axial direction of theleader pin, i.e., in the transverse direction of the magnetic tape 10,by bringing the side edges of the magnetic tape 10 into abutment againstthe shoulders 116 c.

In the fourth example shown in FIG. 9, the outer diameter of the shaftportion 115 is slightly smaller than that of the small diameter portions12 and shoulders 115 c are formed between the shaft portion 115 and eachof the small diameter portion 12. The magnetic tape 10 is positionedwith respect to the leader pin in the axial direction of the leader pinby use of the shoulder 115 c.

In the fifth example shown in FIG. 10, the pin body 114 is the same asthat shown in FIG. 8 but the magnetic tape 10 is fixed to the leader pinby a pair of split clamp members 118 of plastic. That is, the clampmembers 118 are semi-cylindrical in shape and are fixed together byadhesive with the pin body 114 and the leading end portion of themagnetic tape 10 intervening therebetween as shown in FIGS. 11A and 11B.The tip of the leading end portion of the magnetic tape 10 projectingoutside the clamp members 118 is cut after bonding the clamp members118. The leader pin of this example is easy to manufacture and isadvantageous in that positioning of the magnetic tape 10 is easy.

As a sixth example of the leader pin and its modifications, the mainportion 11 may be formed of pair of members 119A and 119B which arebrought into resilient engagement with each other with the leadingportion of the magnetic tape 10 pinched therebetween as shown in FIGS.12A and 12B, 13A and 13B and 14A and 14B, respectively. In the examplesshown in FIGS. 12A and 12B and 13A and 13B, the members 119A and 119Bare hinged to each other at H and the example shown in FIGS. 14A and14B, the members 119A and 119B are separate from each other.

In the seventh example shown in FIGS. 15, 16A and 16B, the main portion11 of the leader pin 4 is formed with a slit 120 diametrically throughthe main portion 11. The slit 120 is flared in cross-section from thecenter of the main portion 11 toward the opening 120 a on the sideopposite to the side from which the leading end portion of the magnetictape 10 is inserted into the slit 120. After the magnetic tape 10 isinserted into the slit 120, a wedge-shaped clamp member 121 ispress-fitted in the slit 120 from the opening 120 a, thereby clampingthe magnetic tape 10 on the main portion 11 as shown in FIG. 16A. Thisexample is advantageous in that the leader pin 4 can be simple instructure. It is preferred that the wedge-shaped clamp member 121 besubstantially the same in the radius of curvature of the outer surfacethereof as that of the leader pin 4.

In a modification of the seventh example shown in FIGS. 17A and 17B, abifurcated wedge-shaped clamp member 123 is used. The clamp member 123is provided with a pair of hooks 123 a on the tips of the arms and themain portion 11 of the leader pin 4 is provided with a slit 122 which isflared in cross-section from the center of the main portion 11 towardthe opening 122 a on the side opposite to the side from which theleading end portion of the magnetic tape 10 is inserted into the slit122 and is provided with a pair of shoulders 122 b. When the clampmember 123 is press-fitted in the slit 122 from the opening 122 a, thearms of the member 123 is once resiliently bent toward each other andthen spring away from each other into engagement with the shoulders 122b, whereby the clamp member 123 and the magnetic tape 10 are preventedfrom being disengaged from the slit 122.

In the eighth example shown in FIGS. 18A to 18D, a slit 124 is formed inthe main portion 11 of the leader pin 4 and the leading end portion ofthe magnetic tape 10 is inserted into the slit 124. The magnetic tape 10is held on the leader pin 4 by winding the magnetic tape 10 around themain portion 11 with the leading end portion inserted into the slit 124as shown in FIG. 18D. In this example, the slit 124 may extend eitherthrough the main portion 11 as shown in FIG. 18B or not through the mainportion 11 as shown in FIG. 18C.

The slit 124 may reach the flanges 13 as shown in FIGS. 19A and 19B sothat the slit 124 can be easily formed, for instance, by wire cutting.Further the slit 124 may be formed so that a thin portion ha is formedon the outer side of the slit 124 as shown in FIG. 19C and the magnetictape 10 may be held in the slit 124 under the resiliency of the thinportion 11 a.

In the ninth example shown in FIG. 20, the magnetic tape 10 is connectedto a temperature-resistant connecting sheet 125. That is, the leader pin4 is formed by plastic molding and when the leader pin 4 is molded, theconnecting sheet 125 is inserted so that the connecting sheet 125 isprojected from the leader pin 4 as shown in FIG. 21A. The connectingsheet 125 is substantially equal in width to the magnetic tape 10 andthe leading end portion of the magnetic tape 10 is connected to theconnecting sheet 125, for instance, by use of splicing tape 126.

By forming a bent portion 125 a or 125 b in the end portion of theconnecting tape 125 as shown in FIG. 21B or 21C or forming a smallopening 125 c in the end portion of the connecting tape 125 as shown inFIG. 21D, bonding strength of the connecting sheet 125 to the leader pin4 can be increased.

The magnetic tape 10 may be bonded to the connecting sheet 125 byheat-sensitive adhesive as shown in FIG. 22.

In the tenth example shown in FIG. 23, a leader tape 128 such asphotographic film which has suitable strength and rigidity is connectedto the leading end of the magnetic tape 10, for instance, by use ofsplicing tape 126 and a slit 129 is formed in the leader pin 4. Theleader tape 128 is provided with a pair of engagement holes 128 a onupper and lower edges thereof.

Further as shown in FIGS. 24A and 24B, a pair of engagement projections130 projects from one side wall of the slit 129 and a retainerprojection 131 projects from the other side wall of the slit 129 at themiddle between the engagement projections 130. The leader tape 128 isinserted into the slit 129 and the engagement holes 128 a are broughtinto engagement with the engagement projections 130 as shown in FIG.24A. The retainer projection 131 pushes the leader tape 128 toward theengagement projections 130, thereby preventing the engagement holes 128a from being disengaged from the engagement projections 130 as shown inFIG. 24B. This example is advantageous in that the leader tape 128 canbe easily connected to the leader pin 4.

In the eleventh example shown in FIGS. 25A to 25C, the pin body 114 isprovided with a pair of inner flanges 132 which separates the shaftportion 115 from the small diameter portions 12 and a clamp member 116which is C-shaped in cross-section is press-fitted on the shaft portion115 between the inner flanges 132 as shown in FIG. 26. The inner flanges132 are spaced from each other by a distance substantially equal to thewidth of the magnetic tape 10 and are used to position the magnetic tape10 with respect to the leader pin 4.

When the distance between the outer surface of the small diameterportion 12 and the outer surface of the outer flange 13 is representedby h, the distance between the outer surface of the shaft portion 115and the outer surface of the inner flange 13 is represented by a, andthe distance between the outer surface of the small diameter portion 12and the outer surface of the inner flange 132 is represented by b asshown in FIG. 27, at least one of a and b is not larger than 2h/3 in anyone of the leader pins shown in FIGS. 25A to 25C.

In the leader pin shown in FIG. 25A, the outer diameter of the shaftportion 115 is equal to that of the small diameter portion 12 anda=b≦2h/3. The clamp member 116 has a length slightly smaller than thedistance between the inner flanges 132.

In the leader pin shown in FIG. 25B, the outer diameter of the shaftportion 115 is also equal to that of the small diameter portion 12 butthe clamp member 116 has a length substantially equal to the distancebetween the inner flanges 132. The clamp member 116 is provided with anannular recess 133 at each end face thereof and the inner flanges 132are received in the recesses 133 when the clamp member 116 is fitted onthe pin body 114.

In the leader pin shown in FIG. 25C, the diameter of the inner flanges132 is substantially equal to that of the outer flanges 13 andaccordingly b=h. However since the shaft portion 115 is larger indiameter than the small diameter portions 12, a≦2h/3. Accordingly, theclamp member 116 is thinner than that employed in the leader pin shownin FIG. 25A or 25B and is formed of hoop (stainless steel or the like ispreferred in view of resistance to corrosion and/or hardness tomagnetize.

Thus in the leader pins of this example, positioning of the magnetictape 10 and the clamp member 116 is facilitated by virtue of the innerflanges 132 and at the same time even if the inner flanges 132 are smallin thickness (about 0.4 to 0.6 mm), there arises no problem with respectto the strength and/or productivity of the leader pins since the heightof the inner flanges 132 from the outer surface of the shaft portion 115and/or the small diameter portions 12 satisfies the aforesaid condition.In the twelfth example shown in FIG. 28, a pair of annular recesses 134are formed on the pin body 112 between the shaft portion 115 and thesmall diameter portions 12, and a pair of annular protrusions 135 areformed on the inner peripheral surfaces of the clamp member 116 at theends thereof. The annular protrusions 135 are received in the annularrecesses 134 on the pin body 114 when the clamp member 116 is fitted onthe pin body 114.

With this arrangement, the clamp member 116 can be accurately positionedwith respect to the pin body 114. Further the magnetic tape 10 can beaccurately positioned with respect to the leader pin 4 by virtue of theannular protrusions 135 on the clamp member 116. Further the annularprotrusions 135 protects the side edges of the magnetic tape 10 when thetape drawing mechanism of the tape drive system is brought intoengagement with the small diameter portions 12. Further since the innerflanges are not used, problems which arise when inner flanges small inthickness and large in height are used can be avoided.

In the thirteenth example shown in FIGS. 29 to 32, the leader pin 4 isformed by left and right pin halves 4L and 4R which are butted togetheralong a plane P including the longitudinal axis of the leader pin 4.

As shown in FIG. 30, the left pin half 4L has an elongated groove 136formed on the plane P to extend in the longitudinal direction of the pinhalf 4L and an elongated protrusion 137 formed on the plane P to extendin the longitudinal direction of the pin half 4L in a positionsymmetrical to the position of the groove 136 about the center line. Athrough hole 138 is formed in the upper flange 13 to extend from theplane P to the outer surface of the flange 13 while an engagementprojection 139 is formed on the lower flange 13 to project from theplane P. The through hole 138 is provided with a pair of engagementshoulders 138 a and the engagement projection 139 comprises a pair ofresilient engagement pieces 139 a each having a hook portion 139 aprojecting outward.

The right pin half 4R is identical to the left pin half 4L except thatthe right pin half 4R is positioned upside down relative to the left pinhalf 4L. That is, when the left and right pin halves 4L and 4R arebutted together with the leading end portion of the magnetic tape 10intervening therebetween, the engagement projection 138 a on each of theleft and right pin halves 4L and 4R is inserted into the through hole138 of the other pin half, and the protrusion 137 of each of the leftand right pin halves 4L and 4R is inserted into the grooves 136 of theother pin half as shown in FIG. 32. The hook portions 139 b of theengagement projections 139 a are engaged with the engagement shoulders138 a of the through holes 138 and hold together the left and right pinhalves 4L and 4R with the magnetic tape 10 pinched therebetween. It ispreferred that the radius of curvature of the end faces of theengagement pieces 139 a be equal to that of the outer surfaces of theflanges 13 so that the outer surfaces of the flanges 13 formed by thepin halves 4L and 4R become smooth.

Further the magnetic tape 10 is firmly clamped between the left andright pin halves 4L and 4R by virtue of the engagement between thegrooves 136 and the protrusions 137.

This example is advantageous from the viewpoint of productivity in thatthe leader pin can be formed by two identical members and assembly ofthe leader pin and clamp of the magnetic tape 10 can be effected at onetime by simply pressing the left and right halves 4L and 4R against eachother.

Instead of fixing the pin halves 4L and 4R to each other by engagementof the flanges 13 as in the thirteenth example, the pin halves 4L and 4Rmay be fixed to each other by fitting a projection 142 on one of theflanges in a recess 141 on the other flange as shown in FIG. 33 andbonding the pin halves 4L and 4R by adhesive. This arrangement isadvantageous in that no hole is formed on the outer surfaces of theflanges.

In the fourteenth example shown in FIGS. 34, 35A, 35B and 36A to 36C,the leader pin 4 is formed by first and second members 4M and 4S. Thefirst member 4M is provided with a main portion 11 in the form of ahollow cylindrical member having an axial hole 143 and a slit 144communicated with the axial hole 143. One of the small diameter portions12 and one of the flanges 13 are formed on the upper end of the mainportion 11 and the axial hole 143 opens in the lower end face of themain portion 11 which is flat. The second member 4S has a shaft portion145 which is inserted for rotation into the axial hole 143 of the firstmember 4M and the other small diameter portion 12 and the other flange13 are formed on the lower end face of the shaft portion 145. The shaftportion 145 is semi-circular in cross-section and has a flat sidesurface 145 a.

When the leader pin 4 is assembled, the shaft portion 145 of the secondmember 4S is inserted into the axial hole 143 of the first member 4Mwith the flat surface 145 a faced so that a space 146 communicated withthe slit 144 is formed inside the axial hole 143 as shown in FIG. 36A.Then the leading end portion of the magnetic tape 10 is inserted intothe space 146 through the slit 144 as shown in FIG. 36B, and then theshaft portion 145 is rotated counterclockwise so that the magnetic tape10 is pinched between the inner surface of the axial hole 143 and thearcuate outer surface of the shaft portion 145 as shown in FIG. 36C.This example is advantageous in that the leader pin is easy to assemble.

The leading end portion of the magnetic tape 10 may be inserted into theaxial hole 143 before the shaft portion 145 is inserted into the axialhole 143.

In the fifteenth example shown in FIGS. 37 to 39, the leader pin 4comprises a pin body 114 and a clamp member 116 which is fitted on thepin body 114 to form the main portion 11. The pin body 114 has a shaftportion 115 which is substantially equal in outer diameter to the smalldiameter portions 12. A protrusion 147 is formed on the outer surface ofthe shaft portion 115 to extend in the longitudinal direction of the pinbody 114 and a pair of short protrusions 147 a for positioning themagnetic tape 10 are formed at the ends of the protrusion 147 to extendin a circumferential direction of the shaft portion 115.

As shown in FIG. 39, the protrusion 147 is shaped so that the mainportion 11 formed when the clamp member 116 is fitted on the shaftportion 115 is substantially circular in cross-section.

The protrusion 147 facilitates positioning of the leading end of themagnetic tape 10 in the longitudinal direction of the tape 10 and theshort protrusions 147 a facilitate positioning of the magnetic tape 10in the transverse direction thereof.

In the sixteenth example shown in FIGS. 40, 41A and 41B, a loop of aleader tape 148 is connected to the leading end of the magnetic tape 10and the pin body 114 is inserted into the loop of the leader tape 148 sothat the shaft portion 115 is opposed to the leader tape 148. Then themagnetic tape 10 is pulled leftward as seen in FIG. 40 so that theleader tape 148 is brought into close contact with the shaft portion 115and then the clamp member 116 is press-fitted on the shaft portion 115with the leader tape 148 intervening therebetween.

The loop of the leader tape 148 may be made around the pin body 114after placing the pin body 114 on the first leader tape. Further themagnetic tape 10 may be connected to the leader pin by way of a loop ofa splicing tape in place of the loop of the leader tape.

The leader tape 148 may be bonded to the magnetic tape 10 by use ofsplicing tape 149 as shown in FIG. 41A. Otherwise, heat-sensitiveadhesive may be applied to the inner surface of the leader tape 148 andthe opposite ends of the leader tape 148 may be bonded to opposite sidesof the leading end portion of the magnetic tape 10 as shown in FIG. 41Bby applying heat to the opposite ends of the leader tape 148 with theleading end portion of the magnetic tape 10 sandwiched therebetween. Inthis case, the leader tape 148 may be bonded to the shaft portion 115 bythe heat-sensitive adhesive, if desired.

It is possible to use a heat-shrinkable leader tape 148 and fix theleader tape 148 to the shaft portion 115 by heating and shrinking theloop of the leader tape 148 after the shaft portion 115 is inserted intothe loop. In this case, the clamp member 116 may be eliminated.

In this example, even when the leader tape 148 is connected to themagnetic tape 10 by use of a splicing tape 149, the length d of thespliced portion can be short as shown in FIG. 41A, whereby adverseeffect of the shoulders formed at the spliced portion can be avoidedwhen the leader pin is drawn into the tape drive system.

In the case where the clamp member 116 is formed of synthetic resin,there is fear that tape holding strength of the clamp member 116 isweakened due to expansion and/or reduction in coefficient of elasticityof the resin when the leader pin is stored or used under an elevatedtemperature. When the clamp member 116 is formed of crystalline resinsuch as polyamide, polyoxymethylene or polybutylene terephthalate andthe temperature of the mold is set lower than the normal temperaturewhen molding the clamp member 116 so that the resin becomes low incrystallinity, reduction in the tape holding strength of the clampmember 116 can be avoided since the crystallinity of the resin isincreased to shrink the clamp member 16 and the coefficient ofelasticity of the clamp member 116 increased as the temperatureincreases.

Further when the outer surface of the shaft portion 115 and/or the innersurface of the clamp member 116 is roughened by graining, etching, sparkerosion or the like, disengagement of the magnetic tape 10 from theleader pin can be prevented.

When the surface roughness Rz of the surfaces is too small, the tapeholding force becomes poor and when the surface roughness of thesurfaces is too large, ejection of the clamp member 116 from the moldbecomes difficult, scrapings of resin are produced when the clamp member116 is press-fitted on the pin body 114 and/or the magnetic tape 10 canbe broken. Accordingly the surface roughness Rz is preferably in therange of 0.7 μm≦Rz≦30 μm and more preferably in the range of 1 μm≦Rz≦20μm.

Further when the clamp member 116 is press-fitted on the shaft portion115 of the pin body 114 with the magnetic tape 10 interveningtherebetween, air can be trapped between the magnetic tape 10 and theclamp member 116 and the magnetic tape 10 is wrinkled. This problem canbe overcome by forming a slit or a hole in the clamp member 116 at thecenter thereof.

In the examples where the clamp member 116 is press-fitted sideways onthe shaft portion 115 with the magnetic tape 10 intervening therebetweenout of the examples described above, there is fear that the magnetictape 10 is broken especially when the magnetic tape 10 is thin. Thisproblem can be overcome by folding the leading end portion of themagnetic tape 10 in two or more as shown in FIGS. 42A to 42C andpress-fitting clamp member 116 on the shaft portion 115 with the foldedportion 150 of the magnetic tape 10 intervening therebetween. The foldedportion 50 also functions as a damper when the magnetic tape 10 ispulled.

Further it is preferred that the clamp member 116 be provided with aflat portion 116 f on at least one part of the outer surface thereof asshown in FIG. 43. For example, when the clamp member 116 is press-fittedon the pin body 114, the clamp member 116 is held by holding jigs 151with its slit faced downward above the pin body 114 and the magnetictape 10 supported on a support 153 and is pressed against the shaftportion 115 by a pusher tool 152.

Accordingly when the flat portions 116 f are in parallel to thedirection of pushing the clamp member 116 by the pusher tool 152,positioning of the clamp member 116 with respect to the holding jigs151. A flat portion 116 f on the side of the clamp member 116 oppositeto the slit limits the direction of pushing the clamp member 116 by thepusher tool 152 and ensures the area at which the pusher tool 152 pushesthe clamp member 116. Further when a flat portion 115 f is provided onthe pin body 114 at the portion facing the support 153, the pin body 114can stably supported on the support 153.

The magnetic tape 10 may be directly bonded to the leader pin by use ofhot-melt adhesive tape 154 and a hot pressing tool 155 as shown in FIG.45. Use of the hot-melt adhesive tape is advantageous in that theadhesive layer can be more uniform in thickness than when adhesive isused and it is not necessary to use solvent.

It is preferred that the outer peripheral surface of each flange 13 beprovided with non-skid treatment such as knurling, diamond knurling andsplining. This is for preventing slip of the leader pin when the leaderpin is chucked by an assembly jig during assemble of the magnetic tapecartridge or by the tape drawing mechanism of the tape drive system.

In the example shown in FIG. 46, the outer peripheral surfaces of theflanges 13 are splined as indicated at K.

It is further preferred that the leader pin be provided with a cutawayportion for determining the angular position of the leader pin in orderto facilitate positioning the leader pin when connecting the magnetictape to the leader pin and when the leader pin is incorporated in thecartridge casing.

In the example shown in FIG. 47A, the upper flange 13 is provided with apair of parallel flat surfaces S. The flat surfaces S are parallel toeach other and to the direction in which the magnetic tape 20 extendsfrom the leader pin. As shown by the chained line in FIG. 47A, anassembly jig 100 chucks the leader pin at the flat surfaces 5, wherebythe assembly jig 100 can chuck the leader pin constantly in apredetermined angular position. As shown in FIGS. 47B and 47C, the flatsurfaces S may be formed only a part of the flange 13 as seen in thedirection of thickness of the flange 13.

It is generally required that the main portion 11 of the leader pin hasa predetermined outer diameter when the leader pin is incorporated inthe cartridge casing. In some of the preceding examples, thisrequirement can be met by properly selecting the outer diameter of theclamp member 116. However this requirement may also be met without useof the clamp member.

That is, in the example shown in FIGS. 48 to 50, the leader pin 4comprises a shaft portion 115, a pair of inner flanges 132 on oppositeends of the shaft portion 115, a pair of small diameter portions 12 onthe outer sides of the inner flanges 132 and a pair of outer flanges 13on the outer sides of the small diameter portions 12. The inner flanges132 are substantially equal in outer diameter to the outer flanges 13.The leading end of the magnetic tape 10 is tacked to the outer surfaceof the shaft portion 115 by adhesive, water or alcohol and the magnetictape 10 is wound around the shaft portion 115 until the outer diameterof the tape roll 216 becomes substantially equal to that of the innerflanges 132 while applying light tension to the magnetic tape 10. Thenthe magnetic tape 10 is bonded to the outermost run of the tape roll 216by adhesive as shown in FIGS. 48 to 50. In FIG. 50, reference numeral217 denotes adhesive, water or alcohol for tacking the leading end ofthe magnetic tape 10 to the shaft portion 115 and reference numeral 218denotes the adhesive for bonding the magnetic tape 10 to the outermostrun of the tape roll 216. In this state, the leader pin 4 isincorporated in the cartridge casing.

In any one of the preceding examples, it is preferred that the leaderpin be formed of corrosion resistant material. As thecorrosion-resistant material, plastic materials such as aliphaticpolyamides (e.g., nylon 6, nylon 66(6,6; 6/6) and the like), aromaticpolyamide, polycarbonate, polybutylene terephthalate, polyphenylenesulfide, polymethyl methacrylate, polyoxymethylene, and the like,plastic materials having an imide group such as polyimide,polyamide-imide, polyether-imide and the like, stainless steel materialssuch as SUS304, SUS306, SUS316, SUS410 and the like may be employed.These materials are also advantageous in that they are hard tomagnetize. That is, when the leader pin is magnetized, magnetism of theleader pin can affect the information recorded on the magnetic tape.When the leader pin is to be formed of the aforesaid plastic materials,it is preferred that the plastic materials be reinforced with glassfibers or carbon fibers.

Further the leader pin may be provided with hard chrome plating.

As shown in FIG. 51, the leader pin 4 on the leading end of the magnetictape 10 is held in a recess 228 formed inside the tape outlet opening 2by a pair of spring members 230 which press the flanges 13 of the leaderpin 4 against the inner surface of the recess 228 when the magnetic tapecartridge is not used.

As shown in FIG. 52, guide surfaces 229 for guiding the leader pin 4into the recess 228 are formed on the inner surfaces of the upper andlower casing halves 1 a and 1 b. It is preferred that the peripheraledges of the upper and lower flanges 13 be chamfered so that they cansmoothly slide on the guide surfaces 229. The recess 228 has upper andlower inner surfaces which are flat and spaced from each other by adistance substantially equal to the length of the leader pin 4. Theguide surfaces 229 are inclined so that they linearly approach eachother toward the recess 228. The slide door 3 is slid back and forthacross the guide surfaces 229 and the upper and lower faces 3 a of theslide door 3 are inclined to conform to the shape of the guide surfaces229.

When the magnetic tape 10 is rewound and the leader pin 4 is retractedinto the recess 228, the flanges 13 slide on the upper and lower guidesurfaces 229 and the leader pin 4 is successfully retracted into therecess 228 even if the center of the leader pin 4 is shifted from thecenter of the recess 228.

Though, in this embodiment, the space between the upper and lower guidesurfaces 229 linearly changes, it may change curvilinearly. That is,each guide surface 229 may be curved. In such a case, the upper andlower end faces 3 a of the slide door 3 are shaped to conform to theshape of the guide surfaces 229.

FIG. 53 shows a modification of the guide surface 229.

In this modification, the guide surface 229 is provided with a V-shapedgroove 233 which extends from the tape outlet opening 2 to the flatrecess 288. The groove 233 is formed over the entire width of the guidesurface 299 and becomes shallower toward the recess 228.

With this arrangement, the flange 13 of the leader pin 4 slides alongthe center of the guide surface 229 at which the groove 233 is deepestand is smoothly guided to the recess 228 in an erected position.

In another modification shown in FIG. 54, the guide surface 229 isprovided with a V-shaped groove 234 which extends from the tape outletopening 2 to the flat recess 288 and becomes smaller in width toward therecess 228.

With this arrangement, the flange 13 of the leader pin 4 slides alongthe center of the guide surface 229 at which the groove 234 is deepestand as the flange 13 approaches the recess 228, the flange 13 comes torun onto the flat surfaces on opposite sides of the groove 234, wherebythe leader pin 4 can be smoothly guided into the recess 228.

As shown in FIGS. 55A and 55B, the guide surface 229 may be providedwith V-shaped groove 235 or U-shaped groove 236 only at the middleportion thereof.

In FIGS. 53, 54, 55A and 55B, reference numeral 237 denotes a slidinggroove along which the slide door 3 is slit. The grooves 233 and 234 inthe modifications shown in FIGS. 53 and 54 may be U-shaped incross-section.

The guide surface and/or the surface of the sliding groove 237 may besubjected to treatment for reducing friction so that the leader pin 4 orthe slide door 3 slides more smoothly.

The treatment may involve, for instance, embossing, application oflubricant such as silicone, or application of a low friction sheet.

1. A magnetic tape cartridge comprising a cartridge casing, a singlereel around which a magnetic tape is wound and which is contained in thecartridge casing for rotation and a leader pin fixed to the leading endportion of the magnetic tape, wherein the improvement comprises that theleader pin comprises a pin body which is provided with a shaft portionon which the leading end portion of the magnetic tape is attached, apair of engagement portions which are formed on opposite ends of theshaft portion and brought into engagement with a tape drawing mechanismof a recording and reproducing system when the magnetic tape cartridgeis loaded in the recording and reproducing system, a pair of innerflanges formed between the shaft portion and the engagement portions anda pair of outer flanges which are formed on the outer ends of theengagement portions and are removably held in the cartridge casing, anda clamp member which is press-fitted sideways on the pin body with theleading end portion of the magnetic tape intervening therebetween,thereby clamping the leading end portion of the magnetic tape on theleader pin, and that when the distance between the outer surface of theengagement portion and the outer surface of the outer flange isrepresented by h, the distance between the outer surface of the shaftportion and the outer surface of the inner flange is represented by a,and the distance between the outer surface of the engagement portion andthe outer surface of the inner flange is represented by b, at least oneof a and b is not larger than 2h/3.
 2. A magnetic tape cartridgecomprising a cartridge casing, a single reel around which a magnetictape is wound and which is contained in the cartridge casing forrotation and a leader pin fixed to the leading end portion of themagnetic tape, wherein the improvement comprises that the leader pincomprises a pin body which is provided with a shaft portion on which theleading end portion of the magnetic tape is attached, a pair ofengagement portions which are formed on opposite ends of the shaftportion and brought into engagement with a tape drawing mechanism of arecording and reproducing system when the magnetic tape cartridge isloaded in the recording and reproducing system, a pair of annulargrooves formed between the shaft portion and the engagement portions anda pair of outer flanges which are formed on the outer ends of theengagement portions and are removably held in the cartridge casing, anda clamp member which is provided with protrusions on its ends and ispress-fitted sideways on the pin body with the protrusions received inthe annular grooves and with the leading end portion of the magnetictape intervening therebetween, thereby clamping the leading end portionof the magnetic tape on the leader pin.
 3. A magnetic tape cartridge asdefined in claim 2 in which the clamp member is provided with an annularrecess on each end face thereof and the inner flange on the pin body isreceived in the annular recess.